by At the end of the year 2023, astronomers made a startling discovery in the Orion Nebula. Using the James Webb Space Telescope (JWST), the team discovered 40 pairs of planetary mass objects – none of which orbited a star. They are called Jupiter-Mass Binary Objects, or JuMBOs.
In short, this discovery directly challenged both theories of star birth and planet formation. The origin of the orbs remained unknown, and it was not clear how such a large collection pairs these bodies came to visit the nursery of the Orion constellation, located about 1,350 light years from Earth.
Now, however, a team of astrophysicists from the University of Nevada and Stoneybrook University think they may have solved the puzzle. The team provides a compelling model to explain how these strange bodies could be expelled from their home systems, going rogue while still paired with a binary partner. The results, if correct, could revolutionize our picture of planetary evolution.
Related: Radio signals from the Orion nebula reveal new details about strange celestial objects: ‘JuMBOS’
“Our simulations show that close interstellar encounters can spontaneously eject pairs of giant planets from their home systems, causing them to orbit each other in space,” Nevada Astrophysics postdoctoral fellow Yihan Wang said in a statement. “These results could significantly change our perception of planetary dynamics and the diversity of planetary systems in our Universe.”
JuMBO Challenge
Explaining JuMBOs has been a challenge because their existence does not fully conform to classically accepted models of star formation or planet formation.
As hot, gaseous and binary bodies, JuMBOs may at first look like they form when regions are too dense in clouds of falling gas and dust. It’s how stars form, and it’s even the mechanism behind so-called “failed stars,” or brown dwarfs, which get their nickname because they fail to gather enough mass to fuse hydrogen with helium in their cores. – a distinctive characteristic of relaxation. .
However, JuMBOS is likely to actually take a different route. The chance that a star has a binary partner, for example, decreases as the star’s mass decreases. For example, about 75% of massive stars are in binary pairs, but only 50% of stars with masses similar to the sun are found with a stellar partner. And the chance of finding a brown dwarf, with masses about 0.75 times that of the sun, in a small binary, approaches zero percent.
On average, brown dwarfs have masses about 75 times that of Jupiter. Therefore, stars less massive than this, one can reason, should ever exist in binaries — certainly not often 40 are found in the same nebula. JuMBOs have masses below the lower end of brown dwarfs, less than 13 times the mass of Jupiter. So what’s going on?
Furthermore, JuMBOs cannot be explained by standard planetary formation models either. These are models you would see from gas left around a parent star, or stars if you are working with a binary system. That’s because, while we know that planets are regularly kicked out of their home systems to become rogue planets, cosmic orphans wandering the cosmos without a parent star, this process should be so violent that it splits apart any planets that might be gravitationally bound.
Since astronomers have found 40 JuMBO pairs in the Orion Nebula alone, it seems to rule out a freak ejection event that caused a planetary pair to be ejected together without splitting apart.
So, to solve the mystery of where JuMBOS might come from, the team performed supercomputer simulations of eviction events. These “N-body” simulations allowed them to explore interactions in tightly packed clusters of stars that could mean giant planets are expelled but remain gravitationally bound to each other. It was concluded that JuMBOs could originate from densely populated star clusters. If this is the case, then these strange free-floating binaries could be quite common.
The team’s findings have ramifications for our understanding of planet formation in general, suggesting that characteristics such as orbital separation between planetary bodies in the JuMBO pair as well as the shape of that orbit may affect the turbulent environmental conditions that influence of them on the birth of the planet.
“It introduces dynamic stellar interactions as an important factor in the development of unusual planetary systems in dense stellar environments,” Rosalba Perna, team member and Stony Brook University professor of physics, said in the statement.
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The team’s research sets the stage for future JuMBO investigations, possibly with the instrument that helped discover these great pairings: The JWST. It also tells researchers that planet formation is a more diverse and exciting process than previously known.
“Understanding the formation of JuMBOs helps us challenge and refine prevailing theories of planet formation,” UNLV team member and astrophysicist Zhaohuan Zhu said in the statement. “Upcoming observations from the JWST could help us do just that, offering new insights with each observation that will help us better formulate new theories on giant planets.”
The team’s research was published Friday (April 19) in the journal Nature Astronomy.
